JPH0212454B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel liquid crystal material that has positive dielectric anisotropy and exhibits a liquid crystal phase over a wide temperature range, and a liquid crystal composition containing the same. Liquid crystal display elements utilize the optical anisotropy and dielectric anisotropy of liquid crystal materials, and depending on the display format, there are TN type (twisted nematic type), DS type (dynamic scattering type), and guest type. There are various types such as host type and DAP type, and the properties of the liquid crystal materials suitable for each type of use are different. However, all liquid crystal materials have in common that they need to be stable against moisture, air, heat, light, etc., and they are also required to exhibit a liquid crystal phase over as wide a temperature range as possible, centered around room temperature. ing. However, at present, there is no single compound that satisfies these conditions, and the current situation is to use liquid crystal compositions obtained by mixing several types of liquid crystal compounds and non-liquid crystal compounds. Especially recently-
Liquid crystal display elements that operate over a wide temperature range of 20°C to 80°C have become required. In order to satisfy such requirements, an effective means is to lower the viscosity, especially the viscosity at low temperatures. However, in general, those with a high clearing point (N-I point) have a high viscosity, and those with a low viscosity, such as alkylphenylcyclohexane derivatives, have a low clearing point. The present inventors have previously discovered a liquid crystal compound with the general formula: 4-[trans-4′-(trans-
4″-alkylcyclohexyl)cyclohexyl]
Invented fluorobenzene and filed a patent application (Japanese Patent Application Laid-Open No. 1983-64626). However, recent advances in liquid crystal display element technology have been remarkable, and there is a demand for display elements that operate at lower to higher temperatures. An object of the present invention is to meet such demands. That is, the present invention is based on the general formula (In the above formula, R represents an alkyl group having 1 to 10 carbon atoms, and X represents either F, Cl, Br, or I.) )-trans-octadecahydro-p-terphenyl and a liquid crystal composition containing at least one thereof.The compound of formula () of the present invention has a low viscosity of about 25 cp at 20°C, but its liquid crystal temperature range is about 100
It has a wide clearing point of ~280°C and a high clearing point, making it a very useful compound as a component of liquid crystal compositions used for liquid crystal display cells that operate in a wide temperature range from low to high temperatures. In addition, although the dielectric anisotropy Δε is about 2, the threshold voltage and saturation voltage of the liquid crystal composition to which the compound of the present invention is added do not increase much compared to the composition without the addition, and are almost the same. It is the rank.
Furthermore, it is stable against light, heat, air, moisture, etc., and has a wide range of applications. Next, regarding the method for producing the compound of the present invention ()
The cases where X in the formula is F, Cl, Br and the case where I are explained separately. First, when X is F, Cl, or Br in formula (), 4-methoxybromobenzene and metallic magnesium are reacted to form 4-methoxyphenylmagnesium bromide, which is then converted into 4-(trans-
4′-alkylcyclohexyl)cyclohexanone (obtained by oxidizing the corresponding cyclohexanol with chromic anhydride) to form 4-
Methoxy-[1'-hydroxy-4'-(trans-
4″-alkylcyclohexyl)cyclohexyl]
Let it be benzene. This was then dehydrated using a potassium hydrogen sulfate catalyst to give 4-methoxy-[4'-(trans-4''-alkylcyclohexyl)cyclohexen-1'-yl]benzene, which was then oxidized using a Raney-nickel catalyst in an ethanol solvent. Pressure, 30
When reduced at ℃, it becomes 4-methoxy-[4′-(trans-4″-alkylcyclohexyl)cyclohexyl]benzene. Since this is a mixture of trans and cis isomers, it is recrystallized with ethanol to give 4-methoxy-[4′-(trans-4″-alkylcyclohexyl)cyclohexyl]benzene.
-Methoxy- [trans-4′-(trans-4″-
alkylcyclohexyl)cyclohexyl]benzene is obtained. This was demethylated with hydrobromic acid in acetic acid, and 4-hydroxy-[trans-
4′-(trans-4″-alkylcyclohexyl)
Obtain cyclohexyl]benzene. Next, this was dissolved in ethanol, and in the presence of a ruthenium catalyst, 180
℃, catalytic reduction at 50Kg/cm ² to obtain trans-4-alkyl-4″-hydroxy-trans-octadecahydro-p-terphenyl. This was dissolved in acetone and oxidized with chromic anhydride to give trans -4-alkyl-4″-one-trans-octadecahydro-p-terphenyl is obtained. A solution of this product in tetrahydrofuran was added to a tetrahydrofuran solution of 4-halogenobenzene magnesium bromide using metallic magnesium as a Grignard reagent.
(trans-4-alkylcyclohexyl)cyclohexyl]cyclohexanone-1'-ol}
Obtain halogenobenzene. When this is dehydrated with potassium hydrogen sulfate, 4-

[4′-[trans-4″-(trans-4-alkylcyclohexyl)cyclohexyl]cyclohexen-1′-yl]halogenobenzene is obtained. Dissolve this in toluene,
Catalytic reduction is carried out using a Raney nickel catalyst to obtain the target trans-4-alkyl-trans-4″-(4-
Halogenophenyl)-trans-octadecahydro-p-terphenyl is obtained. If the above is expressed as a chemical formula, (In the above formula, X represents F, Cl, or Br.) Next, a method for producing an iodide in which X is is described. A solution of trans-4-alkyl-4″-one-trans-octadecahydro-p-terphenyl in tetrahydrofuran was added to a tetrahydrofuran solution of phenylmagnesium bromide, which was made with metallic magnesium as a Grignard reagent, and 1-

[4′-[trans-4″-(trans-4-alkylcyclohexyl)cyclohexyl]cyclohexane-1′-ol]benzene is obtained. When this is dehydrated with potassium hydrogen sulfate, 1-

[4′-[trans-4″-(trans-4-alkylcyclohexyl)cyclohexyl]cyclohexane-1′-ol]benzene is obtained. This is dissolved in toluene and subjected to catalytic reduction using a Raney nickel catalyst.
Trans-4-alkyl-trans-4″-phenyl-trans-octadecahydro-p-terphenyl is obtained. Dissolve this in acetic acid, add iodine,
Iodination with iodic acid yields the desired trans-4-
Alkyl-trans-4″-(4-iodophenyl)-trans-octadecahydro-p-terphenyl is obtained. The chemical formula shown above is as follows. The compounds of the present invention will be explained in more detail with reference to Examples below. Example 1 [Trans-4-propyl-trans-4''-(4-fluorophenyl)-trans-
Production of octadecahydro-p-terphenyl] Put 1.2 g (0.049 mol) of magnesium turnings into a three-necked flask, and add 9.2 g of 4-bromoanisole.
(0.049 mol) dissolved in tetrahydrofuran was slowly added dropwise while stirring in a nitrogen stream while keeping the reaction temperature at 30 to 35°C. The reaction occurred and the magnesium was dissolved and became homogeneous in 3 hours. 4-
This produces methoxyphenylmagnesium bromide. To this, 10.9 g (0.049 mol) of 4-(trans-4'-propylcyclohexyl)cyclohexanone dissolved in tetrahydrofuran to make 50 ml was added dropwise as quickly as possible while maintaining the reaction temperature at 5 to 10°C. After dropping, the temperature was raised to 35°C, stirred for 30 minutes, and then 50 ml of 3N hydrochloric acid was added. The reaction solution is placed in a separatory funnel and extracted three times with 200 ml of toluene. The combined toluene layers are washed with water until the washings become neutral, and the toluene is distilled off under reduced pressure. The remaining oil is -methoxy-[1'-hydroxy-4'-(trans-4''-propylcyclohexyl)cyclohexyl]benzene, and 6 g of potassium hydrogen sulfate is added to it, followed by dehydration at 160°C for 2 hours in a nitrogen stream. .
After cooling, add 200 ml of toluene, separate the potassium hydrogen sulfate, and wash the toluene layer with water until the washing liquid becomes neutral. Then, toluene was distilled off under reduced pressure,
The remaining oil is recrystallized with ethanol to obtain 4-methoxy-[4'-(trans-4''-propylcyclohexyl)cyclohexene-1'-yl]
It's benzene. The total amount of 7.0 g obtained here was dissolved in 120 ml of ethanol together with 1.0 g of Raney nickel catalyst, and catalytic reduction was carried out at normal pressure at 50°C, followed by 500 ml of hydrogen.
was absorbed. Separate the catalyst and directly recrystallize. Since the obtained product is a mixture of cis and trans forms, recrystallization is repeated with ethanol to isolate the trans form. This is 4-methoxy-[trans-4'-(trans-4''-propylcyclohexyl)cyclohexyl]benzene. Dissolve 40 g of this in 400 ml of acetic acid, add 450 ml of hydrobromic acid (47%), and leave for 30 hours. Reflux. After cooling, add a large amount of water to separate the precipitate, and recrystallize the residue with ethanol. Dissolve 8.0 g of this in 400 ml of ethanol, add 1.0 g of ruthenium/carbon, and heat at 180°C at 50 kg/cm ² . Catalytic reduction is carried out for 5 hours. After removing the catalyst, the solvent is distilled off under reduced pressure to obtain trans-4-alkyl-4''-hydroxy-trans-octadecahydro-p-terphenyl. This is dissolved in acetone 4, and 20 ml of a mixed solution of chromic anhydride and concentrated sulfuric acid is added dropwise at a reaction temperature of 0 to 3°C. The reaction is completed when the reaction solution becomes orange and the color no longer disappears, and the reaction solution is neutralized with sodium bicarbonate.
After the solution is filtered under reduced pressure, the solvent is distilled off, extracted with toluene, washed with water, the toluene is distilled off under reduced pressure, and the solution is recrystallized from toluene. This product is 4-[trans-4'-(trans-4''-propylcyclohexyl)cyclohexyl]cyclohexanone.
When a solution of 1.75 g of 4-fluorobromobenzene dissolved in tetrahydrofuran is dropped onto 0.24 g of a magnesium piece, the magnesium reacts and forms 4-
This produces fluorobenzene magnesium bromide. Add the previously prepared 4-[trans-
4′-(trans-4″-propylcyclohexyl)
Cyclohexyl] Add a solution of cyclohexanone dissolved in 50 ml of tetrahydrofuran. At this time, make sure that the temperature does not exceed 30°C, and reflux for 1 hour after dropping. After cooling, add 50ml of 3N hydrochloric acid and extract with 200ml of toluene. After washing with water, the solvent is distilled off, and 1 g of potassium hydrogen sulfate is added thereto, followed by dehydration at 160° C. for 2 hours in a nitrogen stream. After cooling, remove the potassium hydrogen sulfate and dissolve the solution in 200 ml of toluene. Wash the solution with water until the washings become neutral, and distill off the toluene under reduced pressure. The product obtained by recrystallizing it from fresh toluene is 4-{4'-[trans-4''-(trans-4-propylcyclohexyl)cyclohexyl]cyclohexen-1'-yl}fluorobenzene. Dissolve 1.1g of the substance in 50ml of toluene, add 0.5g of Raney-nickel catalyst, and perform catalytic reduction at room temperature and normal pressure.The reaction is followed by gas chromatography, and the reaction is terminated when the raw material disappears.
After separating the catalyst, recrystallization was repeated. The obtained product is the desired trans-4-propyl-trans.
4″-(4-fluorophenyl)-trans-octadecahydro-p-terphenyl. Yield
0.3g, yield 27%. Crystal - Smectic (C-S)
The point is 105.9℃, smekchitsk-nemachik (S-
The N) point was 238°C, and the nematic clear (N-I) point was 279°C. Example 2 The following compound was produced in the same manner as in Example 1. trans-4-heptyl-trans-4″-(4
-chlorophenyl)-trans-octadecahydro-p-terphenyl, C-S point 56.6℃, S-N
Point 248℃, N-I point 274℃. Example 3 [trans-4-butyl-trans-
Production of 4″-(4-iodophenyl)-trans-ocdadecahydro-p-terphenyl] Trans-4-butyl-4″-one-trans-ocdadecahydro-p obtained by the method of Example 1
-4g of terphenyl in 100ml of tetrahydrofuran
The solution was added dropwise to the Grignard reagent obtained by reacting 0.73 g of magnesium with 4.7 g of bromobenzene. After the dropwise addition, the mixture was refluxed for 2 hours, and after cooling, 50 ml of 3N hydrochloric acid was added, and the mixture was extracted with 200 ml of toluene. After washing until neutrality, the solvent is distilled off under reduced pressure.
Add 2 g of potassium hydrogen sulfate to the remaining oil and dehydrate at 160° C. for 2 hours in a nitrogen stream. After cooling, add 200 ml of toluene to remove potassium hydrogen sulfate, wash with water until neutral, and then distill off toluene under reduced pressure. Recrystallized it with toluene and obtained 1
-{4′-[trans-4′-(trans-4″-butylcyclohexyl)cyclohexyl]cyclohexen-1′-yl}benzene. This one is 0.9
Dissolve g in 200ml of toluene and add 0.4
g and perform catalytic reduction at room temperature and pressure, and repeat recrystallization to obtain trans-4-butyl-trans-4''.
Phenyl-trans-ocdadecahydro-p-terphenyl is obtained. Dissolve 0.5g of this in 200ml of acetic acid, 1ml of sulfuric acid, 0.09g of iodic acid, 0.17g of iodine.
g and refluxed for 15 hours. After cooling, the crystals were separated and recrystallized with toluene to obtain the desired trans-4-butyl-trans-4″-(4-iodophenyl)-trans-ocdadecahydro-p.
-It's terphenyl. C-S point 110℃, S-N
The temperature was 238°C at the point, and 298°C at the N-I point. Example 4 (Usage example) Trans-4-propyl (4'-cyanophenyl) cyclohexane 28% Trans-4-pentyl- (4'-cyanophenyl) cyclohexane 42% Trans-4-heptyl- (4'-cyanophenyl) cyclohexane 30 %, the nematic liquid crystal temperature range of the liquid crystal composition is -3 to 52°C. This liquid crystal composition has a cell thickness of
When sealed in a 10 μm TN cell (twisted nematic cell), the operating threshold voltage was 1.5V and the saturation voltage was 2.0V. The viscosity was 24 cp at 20°C. Trans-1-(4-fluorophenyl)- shown in Example 1 of the present invention was added to 98 parts of the above liquid crystal composition.
The N-I point of the liquid crystal composition containing 2 parts of trans-4''-propyl-trans-ocdadecahydro-p-terphenyl expands to 55.5°C, and the operating threshold voltage of the liquid crystal composition sealed in the above cell is 1.5V and saturation. The voltage is
It remained unchanged at 2.0V. Also, the viscosity at 20℃ is 24cp
It didn't change. As described above, by adding the compound of the present invention, the nematic temperature range of the liquid crystal composition could be expanded without changing the viscosity or voltage value.

Claims (1)

[Claims] 1. General formula (In the above formula, R represents an alkyl group having 1 to 10 carbon atoms, and X represents either F, Cl, Br, or I.) )-trans-octadecahydro-p-terphenyl. 2 General formula (In the above formula, R represents an alkyl group having 1 to 10 carbon atoms, and X represents either F, Cl, Br, or I.) )-trans-octadecahydro-p-terphenyl at least 1
A liquid crystal composition characterized by containing seeds.